The DOT or Department of Telecommunications has divided India into various telecom circles or cellular zones. Within each circle, the call is treated as local and across the circles it becomes a STD call.

At present there are around 22 telecom circles or cellular zones in India. All mobile numbers in India have the prefix 7, 8 or 9.

Mobile network details are subject to change as the Mobile number portability (MNP) is available in most of the circles.